DPDK patches and discussions
 help / color / mirror / Atom feed
From: Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com>
To: dev@dpdk.org
Subject: [dpdk-dev] [PATCH 1/2] mbuf: Introduce IND_ATTACHED_MBUF flag
Date: Mon, 16 Feb 2015 16:08:32 +0000	[thread overview]
Message-ID: <1424102913-18944-2-git-send-email-sergio.gonzalez.monroy@intel.com> (raw)
In-Reply-To: <1424102913-18944-1-git-send-email-sergio.gonzalez.monroy@intel.com>

Currently for mbufs with refcnt, we cannot free mbufs with external memory
buffers (ie. vhost zero copy), as they are recognized as indirect
attached mbufs and therefore we free the direct mbuf it points to,
resulting in an error in the case of external memory buffers.

We solve the issue by introducing the IND_ATTACHED_MBUF flag, which indicates
that the mbuf is an indirect attached mbuf pointing to another mbuf.
When we free an mbuf, we only free the direct mbuf if the flag is set.
Freeing an mbuf with external buffer is the same as freeing a non attached mbuf.
The flag is set during attach and clear on detach.

So in the case of vhost zero copy where we have mbufs with external
buffers, by default we just free the mbuf and it is up to the user to deal with
the external buffer.

This patch would allow the removal of the RTE_MBUF_REFCNT config option,
setting refcnt for all mbufs permanently.

The patch also modifies the vhost example as it was using the
RTE_MBUF_INDERECT macro to detect if it was an mbuf with external buffer.

Signed-off-by: Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com>
---
 examples/vhost/main.c      |  6 ++++--
 lib/librte_mbuf/rte_mbuf.h | 15 +++++++++------
 2 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/examples/vhost/main.c b/examples/vhost/main.c
index 3a35359..5e341d6 100644
--- a/examples/vhost/main.c
+++ b/examples/vhost/main.c
@@ -139,6 +139,8 @@
 /* Number of descriptors per cacheline. */
 #define DESC_PER_CACHELINE (RTE_CACHE_LINE_SIZE / sizeof(struct vring_desc))
 
+#define MBUF_EXT_MEM(mb)   (RTE_MBUF_FROM_BADDR((mb)->buf_addr) != (mb))
+
 /* mask of enabled ports */
 static uint32_t enabled_port_mask = 0;
 
@@ -1567,7 +1569,7 @@ txmbuf_clean_zcp(struct virtio_net *dev, struct vpool *vpool)
 
 	for (index = 0; index < mbuf_count; index++) {
 		mbuf = __rte_mbuf_raw_alloc(vpool->pool);
-		if (likely(RTE_MBUF_INDIRECT(mbuf)))
+		if (likely(MBUF_EXT_MEM(mbuf)))
 			pktmbuf_detach_zcp(mbuf);
 		rte_ring_sp_enqueue(vpool->ring, mbuf);
 
@@ -1630,7 +1632,7 @@ static void mbuf_destroy_zcp(struct vpool *vpool)
 	for (index = 0; index < mbuf_count; index++) {
 		mbuf = __rte_mbuf_raw_alloc(vpool->pool);
 		if (likely(mbuf != NULL)) {
-			if (likely(RTE_MBUF_INDIRECT(mbuf)))
+			if (likely(MBUF_EXT_MEM(mbuf)))
 				pktmbuf_detach_zcp(mbuf);
 			rte_ring_sp_enqueue(vpool->ring, (void *)mbuf);
 		}
diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
index 16059c6..12e7545 100644
--- a/lib/librte_mbuf/rte_mbuf.h
+++ b/lib/librte_mbuf/rte_mbuf.h
@@ -162,6 +162,8 @@ extern "C" {
 /** Tell the NIC it's an outer IPv6 packet for tunneling packet */
 #define PKT_TX_OUTER_IPV6    (1ULL << 60)
 
+#define IND_ATTACHED_MBUF    (1ULL << 62) /**< Indirect attached mbuf */
+
 /* Use final bit of flags to indicate a control mbuf */
 #define CTRL_MBUF_FLAG       (1ULL << 63) /**< Mbuf contains control data */
 
@@ -305,13 +307,12 @@ struct rte_mbuf {
 /**
  * Returns TRUE if given mbuf is indirect, or FALSE otherwise.
  */
-#define RTE_MBUF_INDIRECT(mb)   (RTE_MBUF_FROM_BADDR((mb)->buf_addr) != (mb))
+#define RTE_MBUF_INDIRECT(mb)   (mb->ol_flags & IND_ATTACHED_MBUF)
 
 /**
  * Returns TRUE if given mbuf is direct, or FALSE otherwise.
  */
-#define RTE_MBUF_DIRECT(mb)     (RTE_MBUF_FROM_BADDR((mb)->buf_addr) == (mb))
-
+#define RTE_MBUF_DIRECT(mb)     (!RTE_MBUF_INDIRECT(mb))
 
 /**
  * Private data in case of pktmbuf pool.
@@ -713,7 +714,7 @@ static inline void rte_pktmbuf_attach(struct rte_mbuf *mi, struct rte_mbuf *md)
 	mi->next = NULL;
 	mi->pkt_len = mi->data_len;
 	mi->nb_segs = 1;
-	mi->ol_flags = md->ol_flags;
+	mi->ol_flags = md->ol_flags | IND_ATTACHED_MBUF;
 	mi->packet_type = md->packet_type;
 
 	__rte_mbuf_sanity_check(mi, 1);
@@ -744,6 +745,8 @@ static inline void rte_pktmbuf_detach(struct rte_mbuf *m)
 			RTE_PKTMBUF_HEADROOM : m->buf_len;
 
 	m->data_len = 0;
+
+	m->ol_flags = 0;
 }
 
 #endif /* RTE_MBUF_REFCNT */
@@ -757,7 +760,6 @@ __rte_pktmbuf_prefree_seg(struct rte_mbuf *m)
 #ifdef RTE_MBUF_REFCNT
 	if (likely (rte_mbuf_refcnt_read(m) == 1) ||
 			likely (rte_mbuf_refcnt_update(m, -1) == 0)) {
-		struct rte_mbuf *md = RTE_MBUF_FROM_BADDR(m->buf_addr);
 
 		rte_mbuf_refcnt_set(m, 0);
 
@@ -765,7 +767,8 @@ __rte_pktmbuf_prefree_seg(struct rte_mbuf *m)
 		 *  - detach mbuf
 		 *  - free attached mbuf segment
 		 */
-		if (unlikely (md != m)) {
+		if (RTE_MBUF_INDIRECT(m)) {
+			struct rte_mbuf *md = RTE_MBUF_FROM_BADDR(m->buf_addr);
 			rte_pktmbuf_detach(m);
 			if (rte_mbuf_refcnt_update(md, -1) == 0)
 				__rte_mbuf_raw_free(md);
-- 
1.9.3

  reply	other threads:[~2015-02-16 16:12 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-16 16:08 [dpdk-dev] [PATCH 0/2] Removal of RTE_MBUF_REFCNT Sergio Gonzalez Monroy
2015-02-16 16:08 ` Sergio Gonzalez Monroy [this message]
2015-02-16 16:08 ` [dpdk-dev] [PATCH 2/2] Remove RTE_MBUF_REFCNT references Sergio Gonzalez Monroy
2015-02-18  9:16   ` Olivier MATZ
2015-02-18  9:35     ` Bruce Richardson
2015-02-18  9:48       ` Ananyev, Konstantin
2015-02-18 10:00         ` Bruce Richardson
2015-02-18 10:14           ` Olivier MATZ
2015-02-18 10:22             ` Ananyev, Konstantin
2015-02-18 10:22             ` Bruce Richardson
2015-02-18 10:33               ` Olivier MATZ
2015-02-18 10:37                 ` Bruce Richardson
2015-02-18 10:47                   ` Olivier MATZ
2015-02-18 10:47                 ` Ananyev, Konstantin
2015-02-18 11:01                   ` Olivier MATZ
2015-02-18  9:52       ` Olivier MATZ
2015-02-16 20:47 ` [dpdk-dev] [PATCH 0/2] Removal of RTE_MBUF_REFCNT Stephen Hemminger
2015-02-17  8:43   ` Gonzalez Monroy, Sergio
2015-02-18 11:03 ` [dpdk-dev] [PATCH v2 " Sergio Gonzalez Monroy
2015-02-18 11:03   ` [dpdk-dev] [PATCH v2 1/2] mbuf: Introduce IND_ATTACHED_MBUF flag Sergio Gonzalez Monroy
2015-02-18 11:03   ` [dpdk-dev] [PATCH v2 2/2] Remove RTE_MBUF_REFCNT references Sergio Gonzalez Monroy
2015-02-18 12:05   ` [dpdk-dev] [PATCH v2 0/2] Removal of RTE_MBUF_REFCNT Ananyev, Konstantin
2015-02-23 18:36     ` Thomas Monjalon

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1424102913-18944-2-git-send-email-sergio.gonzalez.monroy@intel.com \
    --to=sergio.gonzalez.monroy@intel.com \
    --cc=dev@dpdk.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).